Field of the Invention
This invention relates, in general, to gas indicating devices and, in particular, to a new and useful colorimetric gas dosimeter which is adapted to be worn on a person for the detection of gas.
The invention concerns a colorimetric gas dosimeter, which contains a color indicator disc on one side wall in a box-shaped, flat measuring chamber, and in which the gas inlet lies in the side wall of the measuring chamber away from the color indicator disc.
Colorimetric gas dosimeters that can be worn, like radiation dosimeters, on the clothing of workers are known in several forms from the DE-GM No. 79 16 943, for example. A uniform deposition of the harmful substances to be detected on the surface of an indicator disc is desired in these devices. Independence from air currents at the gas inlet is provided by a damper layer located in the front, resulting in a gas exchange by diffusion. The harmful substance component diffuses through a quite central layer of flow in the measuring chamber onto the surface of the indicator layer, causing the color reaction.
Because of the attempted uniform deposition on the indicator layer, a multi-chambered device is used when a distinction is to be made between different volumes of the gaseous harmful substance to be measured, with each chamber having a different sensitivity due to changes in measuring with the same indicator layer. The user can recognize how strong his exposure to a given harmful substance was by checking the individual discolored indicator discs from the most sensitive to the least sensitive chamber.